The Following GX Duelists in the Battle City Tournament

These will be three separate scenarios.

In each scenario, replace Yugi with the designated GX duelist.
They have to go through every duel Yugi did from the very first battle with the Rare Hunter/Ghoul with Exodia up until (if they make it that far) the finals with Yami Marik.

So, how do they do?

1. Aster
2. Chazz
3. Season 2 Zane w/Cyberdark Deck
4. End of Season 2 Jaden

EDIT:
They don't have to do the tag duel with Kaiba. Unless you want to have them try that

zane would phuck shit up

all of them would most likely stop at Seto Kaiba or maybe the Rare Hunter who was controled by Marik and has Slifer the Sky Dragon. Kaiba has Obelisk the Tormentor which is one of the God card which is unaffected by trap, and magic can only affect Obelisk in one turn only. Even if Obelisk destroyed, Kaiba still has Blue Eyes White Dragon and Ultimate Dragon. Don't forget that Kaiba has CCV which would wreck their deck especially Zane who'll have his Cyber Dragon destroyed while Judai/Jaden still has a hope since most of the Elemental Heroes doesn't have more than 1500 ATK points.

Knowing YGO anime's style that a monster with enormous ATK "must be" destroyed with ATK, Jaden would waste his resources to annihilate Obelisk. The only thing that would save Jaden is if he can perform an asspull just like what Yusei always did (Wait... Jaden always too...). Oh, and even Jaden lost to Kaibaman while Kaibaman has a downgrade version of Kaiba's real deck.

EDIT : And if they can't stop Exodia, they'll stop in the first round.